The invention relates to a quick release device particularly suited for anchor lines, and in particular to the quick release of anchorage lines to ships, platforms and all marine drilling appliances. The invention also relates to a method of anchorage.
The need to release a drilling appliance arises, for example, in the case of uncontrolled eruption of the well. It may also arise when the appliance is in a zone in which icebergs are liable to drift.
As these appliances are fastened to eight to ten anchorage lines consisting of large-diameter cables or large-link chains, a relatively long period of at least ten hours is required before the appliance can be released. As it is fastened to anchorage lines arranged in several directions, the appliance cannot be positioned vertically over each anchor so as to be able to pull it away from the bottom and weigh it. It is therefore necessary to have recourse to a service barge which lifts each anchor, one after the other, to enable each anchor line to be taken on board. This operation requires a relatively calm sea, as the service barge must recover the marker-buoy to which the cable fastened to the crown of the anchor is attached. It will easily be appreciated that in the case of a bad sea, the drilling appliance is immobilized for several days, or even several weeks, with the risks which attend this immobilization in swells sometimes attaining 25 metre troughs, before this operation can be carried out. Given the very high cost of hire of drilling appliances, more than one hundred-thousand francs per day, the economy realized by instant release of the anchorage will be appreciated.